1. Field of the Invention
The present invention relates to a plasma display control system for driving a plasma display at the display timing of a CRT display.
2. Description of the Related Art
In general, in display control of a CRT display, a vertical blanking period (0.0008 sec to 0.0013 sec) including a vertical sync signal and front and back porches at the beginning and end of this signal is necessary. On the other hand, in display control of a plasma display, the above-mentioned long vertical blanking period is not required. Therefore, the plasma display and the CRT display have a different display timing for display drive control. Therefore, in a laptop type personal computer which has a plasma display and a CRT display which can be connected as an external device, a display timing circuit is required to control the plasma display and the display timing circuit must also drive the CRT display. Furthermore, a switching circuit for switching the display timings is also required, resulting in a complex arrangement.
In the CRT display, since a front (1.27 .mu.sec) and a back porch (3.81 .mu.sec) must be large to provide a display margin so that if a frame is offset slightly (by several characters) in a horizontal or vertical direction, the entire frame can still be displayed.
On the other hand, since the plasma display has no display margin, when the identical frame is displayed using the same display timing as the CRT display, the frame will be partially omitted and is not displayed on the plasma display.